As federal prosecutors prepared subpoenas for one of his colleagues and the Navy disbarred a defense contractor with close ties to him, John Murtha last week took an unusual step in response to the ethics imbroglio that seems to be intensifying around him.

He sent thank-you notes to fellow Democrats.

It’s not clear how many House Democrats got the notes — or why. According to aides who have seen copies, the notes said only “Thanks for your support,” and they seem to have been signed by Murtha himself.

By Murtha’s standards, it was a big step.

For months now, the Pennsylvania Democrat has been the subject of unflattering headlines and a GOP push — slowly building momentum —for an ethics probe into the dealings he and other Democratic appropriators had with the now-defunct PMA Group. Last week, one of those lawmakers, Rep. Pete Visclosky of Indiana, was subpoenaed, and the Navy reported that it had disbarred Kuchera Defense Systems, a company to which Murtha has repeatedly steered earmarks, for “alleged fraud.”

Most lawmakers in Murtha’s position would hire lawyers — as Visclosky has — or engage a PR specialist or mount an aggressive public defense, as Ways and Means Committee Chairman Charles Rangel did when he asked for an ethics investigation into himself. But Murtha has chosen a different path — no lawyers, no public defense and an in-your-face defiance whenever he’s asked about the ethics issues.

“[Murtha is] not really troubled about it, as others might be,” insisted one House source close to Murtha. “His theory is not to talk, so he’s not talking.”

At least not when he can avoid it.

While many members might find a scandal over earmarks an opportune time to steer clear of public ties with industry, Murtha went right ahead with his annual Showcase for Commerce in Johnstown, Pa., last week — an event underwritten by some of the same defense firms to whom he’s steered federal funds.

When reporters covering the event asked Murtha about Kuchera’s disbarment, the Johnstown Tribune Democrat reported Murtha shot back: “What’s that got to do with me? What do you think? Do you think I oversee these companies? That’s the Defense Department’s job. That’s not my job. You guys write these stories — you don’t have a clue what this is all about.”

The Kuchera brothers, Bill and Ron, and their employees have given more than $65,000 to Murtha’s reelection campaign and leadership political action committee, and Murtha held a major fundraiser at Bill Kuchera’s ranch last fall. At the same time, Murtha has secured nearly $15 million in earmarks for the company, and he helped the company win a missile contract that could be worth $100 million.

When reporters asked Murtha on Friday whether he’d hired a defense attorney to deal with the PMA scandal, he snapped, “What kind of question is that?” And then he walked out.

But the subpoenas served on Visclosky’s office, campaign and employees last week suggest that Murtha and his fellow appropriators won’t be able to dodge questions about PMA forever.

The lobbying shop imploded earlier this year, following an FBI raid on its offices in November. Its founder, former Appropriations Committee aide Paul Magliocchetti, has moved to Florida and retired, while its other lobbyists have moved on to different firms. The Justice Department is reportedly looking into whether Magliocchetti used “straw donors” to steer hundreds of thousands of dollars in campaign contributions to lawmakers who in turn pushed earmarks worth tens of millions for its clients.

Visclosky said he would cooperate with the federal subpoenas “consistent with my constitutional obligations to Congress and my duties and responsibilities to my constituents.”

But while Visclosky was a big recipient of PMA-related campaign cash, no one was more popular with the firm than Murtha.

The Pennsylvania Democrat received $2.38 million in campaign contributions from PMA and its clients over the past 10 years, according to the Center for Responsive Politics, a watchdog group. During the same time period, Murtha secured millions in earmarks — more than $97 million in 2007-08 alone — to PMA’s clients.

Murtha denies any wrongdoing in his dealings with PMA or Magliocchetti, and Murtha’s aides and Democratic allies insist that the veteran lawmaker isn’t the target of the Justice Department’s criminal investigation into PMA.

His office says he has not been subpoenaed.

In the House, Rep. Jeff Flake (R-Ariz.) has repeatedly introduced a resolution calling for an ethics committee investigation into Murtha and the other appropriators. While it hasn’t yet won majority support, it’s steadily picking up votes from Democrats — 29 voted for the most recent version — particularly ones who don’t come from Murtha’s generation of “you scratch my back, I’ll scratch yours” Old Bulls.

Until his recent thank-you notes, Murtha hasn’t acknowledged Flake’s repeated requests for an ethics investigation. Instead, the towering former Marine remains unbowed and unapologetic, telling the Pittsburgh Post-Gazette recently, “If I’m corrupt, it’s because I take care of my district.”

Speaker Nancy Pelosi (D-Calif.), a close Murtha friend and political ally, has remained tightlipped about him as well. One Democrat says Pelosi “won’t even discuss” Murtha and “won’t even consider” any move to replace him as the head of the Defense Subcommittee.

“[Pelosi] is totally committed to him,” said this lawmaker, speaking on the condition of anonymity. “She won’t even discuss him with anyone else. It’s a ‘no-go’ zone.”